I'm pretty sure the original permission still stands, so as long as its built as the original granted planning permission states, then they should be fine.
It definitely still stands.
Been involved in the planning process for years, North and South of the border.
It's VERY common to get planning permission by taking the advise of planning officers and following their recommendations.
Then after approval apply for new planning permission with tweaks to the original plans (like a bigger house/extra rooms).
Sometimes there are 8, 10, 12 sets of plans submitted for approval on larger sites.
If every new application invalidated the preceding application it would cause chaos.
I'm also a fully certified homes under the hammer watcher and see my mate Dion talking about this all the time